1. Field of the Invention
The present invention relates generally to an inflatable packer attached to a supporting element for sealing an annular space in a well bore and, more particularly, to an improved inflatable packer for use in high temperature environments. Specifically, the present invention relates to improved inflatable packers having high pressure resistance to prevent blow outs under high temperature and pressure situations.
2. Description of the Prior Art
Inflatable packers are down-holed tools useful in the well drilling industry as well as in other piping applications. An inflatable packer is internally inflatable utilizing a fluid for the purpose of sealing off an annular space in the well or pipe, for example between the casing and the well bore, or between a drill string or other retrievable tool and an outer well casing. Although not so limited, the packer of the present invention is particularly suited for isolating zones within a well for such purposes as cementing, fracturing, treating, testing, preventing gas migration to the surface, and for gravel pack operations.
Inflatable packers normally include an elastomeric body and a reinforcement sheath or layer. A recognized problem with prior art packers has been the inability to securely anchor the reinforcing elements of the packer body to end sleeve members or ferrules which couple the packer assembly to the casing, drill string or other down-hole tool. Typically, the reinforcing elements have been clamped at their ends and, in some instances, the mechanical clamping has occurred through the use of epoxy adhesives along the interface between the reinforcement element free ends and a portion of the sleeve termination to provide both adhesive connection as well as a potential wedging connection. Other problems in practice include the tendency of the body of the packer to rupture or develop pinhole leaks and the failure of the body to return substantially to its original uninflated configuration after repeated inflation/deflation cycles. Examples of such prior art devices include those disclosed in U.S. Pat. Nos. 2,643,722, 2,872,230, 2,970,651, 3,028,915, 3,035,639, 4,191,383, 4,700,954 and Canadian Patent No. 702,327.
A recent attempt to provide a packer construction which overcomes the aforementioned problems while also withstanding high internal inflation pressures and external differential pressures across the packer elements is disclosed in U.S. Pat. No. 4,614,346, issued Sep. 30, 1986, and assigned to the assignee of the present invention, the contents of which are specifically incorporated herein by reference. Unfortunately, while such inflatable packer constructions are quite adequate in many applications, high temperature applications encountered in the instances of deep well drilling have caused some unique problems. In inflatable packer devices utilizing epoxy based resins or other adhesive materials to anchor the ends of the reinforcement to the end sleeve of the packer assembly, either through adhesive or wedging capabilities, the packers tend to loose their adhesive and anchoring capability at such high temperatures due to the softening of the epoxy resin material. In such instances, the ends of the packers tend to rupture upon inflation due to the pulling out or removal of the reinforcement members resulting from softening of the anchoring material. Therefore, there remains a need for an inflatable packer construction wherein the reinforcement sheath or elements are capable of being anchored and remain anchored even during repeated high temperature applications.